An enormous work of data recovery is being made at the historical records of IEO tide gauges. The main objective is to avoid losses due to paper records damages and facilitate an easy access to information. In addition, a future digitalisation of near-continuous data will permit to identify high-frequencies signals like tsunamis or seiches. Identification and study importance of these phenomena is closely related with their possible impacts on coast: floodings, economical losses, etc. As example, a previous analysis of the tsunami associated to Algeria earthquake on 21-may
-2003 is show
